sendgrid substitutions

TL;DR

Put the exact substitution tag in your template, then map that exact string in personalizations[0].substitutions. The keys must match the template placeholders character for character, dashes included. If nothing substitutes, the key and the template tag differ, or you are using a dynamic template, which needs dynamic_template_data instead.

sendgrid substitutions

Use this when

• Template emails go out with raw tags like -name- still visible.
• You are migrating legacy templates to the v3 mail send API.
• You need per-recipient values in subject, body, or headers.

Not for this skill when

• You use dynamic templates with handlebars syntax. Those take dynamic_template_data, not substitutions.
• Every recipient gets the same value. Use a global substitution or hardcode it.

Steps

1. Open the template and note the exact tag text, e.g. the string -name- in the subject or body. Verify: you can quote the tag exactly.
2. Build the payload with the key equal to the tag: personalizations: [{ "to": [{ "email": "[recipient email]" }], "substitutions": { "-name-": "Ruth" } }]. Verify: the key string equals the template tag exactly.
3. Send a test to one address. Verify: the received email shows Ruth, not -name-.
4. Add global substitutions for values shared by all recipients. Verify: they appear in every recipient's copy.
5. For per-recipient uniqueness, give each personalization its own substitutions object. Verify: two test recipients get different values.

Variant phrasings

sendgrid substitution tags not working

Same root cause 9 times out of 10: the key does not match the tag.

sendgrid personalizations substitutions

Covers the API-path search.

sendgrid template variables legacy

Legacy templates use substitutions; dynamic templates do not.

Compatibility: SendGrid v3 Mail Send API. Legacy transactional templates only. Dynamic templates (handlebars) ignore substitutions entirely.

Why it happens

Substitutions are plain string replacement keyed on the exact tag text. SendGrid does no fuzzy matching, no case folding, and no warning when a key matches nothing. So a template containing -Name- with a key of -name- silently passes through, and dynamic templates silently ignore substitutions because their engine reads dynamictemplatedata.

Edge cases / pitfalls

• Substitution keys are case-sensitive. -NAME- and -name- are different keys.
• Very long values can push the payload past size limits. Keep them short.
• Set substitutions inside each personalization. A key on the top-level object does not always inherit into personalizations.
• Never put secrets in substitution values. They travel in the clear.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Y2U2IoOF7UUnvN9Xs-of6w

Resolved from the public thread: https://vectle.com/posts/pst_Y2U2IoOF7UUnvN9Xs-of6w

Thread query: sendgrid substitutions

TL;DR: Put the exact substitution tag in your template, then map that exact string in personalizations[0].substitutions. The keys must match the template placeholders character for character, dashes included. If nothing substitutes, the key and the template tag differ, or you are using a dynamic template, which needs dynamic_template_data instead.